A titanium oxide having a monoclinic β-type structure has recently attracted remarkable attention as a high-capacity negative electrode material. The number of lithium ions which can be inserted into lithium titanate having a spinel structure (Li4Ti5O12), which has been made practicable, is three per unit chemical formula. In other words, the number of lithium ions which can be inserted is 3/5 per titanium ion. Therefore, the maximum number is theoretically 0.6. Such a lithium titanate having a spinel structure has a theoretical capacity of about 170 mAh/g.
On the contrary, the number of lithium ions which can be inserted into titanium oxide having a monoclinic β-type structure is a maximum of 1.0 per titanium ion. This titanium oxide therefore provides a theoretical capacity as high as about 330 mAh/g and a reversible capacity as high as about 240 mAh/g. Then, it is considered that the capacity of a battery can be improved by using titanium oxide having a monoclinic β-type structure.
However, the electrode density is difficult to be raised when titanium oxide having a monoclinic β-type structure is used as a negative electrode material. Thus, it is necessary to excessively press the electrode in the production of the electrode. As a result, there is the case where the adhesiveness of the electrode is damaged. Further, the titanium oxide having a monoclinic β-type structure is largely expanded and shrunk when a battery is charged/discharged. For this, the electrode is significantly deteriorated by repeat charging/discharging a number of times. These facts show that there is a problem in that a nonaqueous electrolyte battery using titanium oxide having a monoclinic β-type structure as the negative electrode material has low input/output performance.